The present invention relates to a lock mechanism and more particularly to a lock mechanism which can be latched in an engaged position.
Locks which provide security on one side and easy and quick operation from the other aide are used widely, particularly for doors providing an emergency exit from a building.
Commonly such locks use an engineered rack and pinion operating mechanism to operate several strong bolts simultaneously to secure the door. The door is thus secured at various points around its perimeter to provide security and prevent access from one side of the door. When such a door is an emergency exit it is necessary to comply with safety requirements to provide an operating lever inside which will operate by a single simple movement to retract the bolts and unlock the door to allow a safe and quick exit through the door from the building. Typically, a horizontal bar is provided on such doors for the operation of the lock mechanism.
Thus for lock mechanisms used for such doors there are conflicting requirements. One requirement is the security to prevent access from one side whilst the other requirement is a safety requirement to provide for simple and quick operation of the lock mechanism from the inside to allow the door to be unlocked quickly in an emergency. Thus in one aspect the present invention is directed towards a solution to this problem.
The lock mechanisms currently available with a direct drive mechanism to the bolts such as a rack and pinion do not provide adequate security since they do not provide resistance to the application of pressure to the ends of the bolts. It is to this problem that a further aspect of the present invention is directed.